In my application Ser. No. 34,773, there is disclosed a high pressure pulsation dampener surge absorber that uses a silicone base liquid as the dampening media rather than a compressed gas. Reference is hereby made for incorporating the entire disclosure of Ser. No. 34,773 including the discussion of background art therein in this application as well as that of Ser. No. 955,929 as if fully set forth herein.
Nongas pulsation dampeners, such as disclosed in U.S. Pat. No. 3,731,709 are known. In general, they have employed internal guides for changing flow direction and which will change their frequency dampening characteristics with changes in working fluid density.
During well drilling operations it is desirable to obtain information from tools connected downhole in the drill string. In fact, it is desirable to obtain such information on a continuous basis without interfering with well drilling operations. To obtain such information in the past it was often necessary to shut down drilling operations while a tool was run downhole to determine the desired information, such as borehole deviation from vertical. To overcome this disadvantage, downhole tools have been developed to signal such information to the surface using pressure pulses in the circulating drilling fluid. As the instruments at the surface reading such pressure pulses have been unable to distinguish between the pressure pulse signals and the pressure pulses originating in the discharge of the positive displacement circulating pumps, such signal systems have been unreliable.